（1）honeycomb girder gantry crane
 
Gantry crane produced by ZZHZ accesses to national patent with isosceles triangle honeycomb type main girder, it features light self-weight, high stiffness, low deflection and high wind resistance. The main longitudinal girder keeps load-bearing steel plates at two sides of box girder, removes non-load-bearing steel plates at upper and bottom parts, directly welds two sides steel plates together, replaces U-steel at bottom parts, thus the honeycomb girder structure is designed, it keeps the advantages of box girder and overcomes its shortcoming: too heavy. 
（2）honeycomb girder
 
Crane main girder------advantages to use honeycomb girder
Main girder design is in accordance with crane rated lifting capacity, span and lifting height. Most of crane main girders at home and aboard are box girder and truss girder, honeycomb girder as a new type main girder has not got approval from many customers, and the main reason is that design calculation for honeycomb girder is more complicated than box girder and truss girder, that traditional calculation can not get an accurate results on stress of honeycomb hole in web plate. With popular application of finite element software, calculation on honeycomb girder strength, stiffness and stability has been greatly increased.
Below are comparison analyses among honeycomb girder, box girder and truss girder:
The first kind of girder chooses H structural steel specification H240×150×6×8;
The second kind of girder chooses H structural steel specification H240×150×6×8 to make hexagonal honeycomb girder, see details in attached drawing (1);
The third kind of girder chooses H structural steel specification H360×150×6×8.
Basic parameters are as below:
Girder length 5.4m, applied load at mid-span 20kN, elasticity modulus E=20600MPa, finite element calculation results for three kinds of simply supported beam see the form below.
Girder type H240×150×6×8 Honeycomb girder H360×150×6×8 Remark 
Displacement
mm X direction -0.009 0.009 -0.006 0.006 -0.005 0.005
Y direction -8.9 0 -4.2 0 -3.5 0
Z direction 0 1.1 -0.008 0.689 0 0.655
Total 8.9 4.24 3.49
Stress 
MPa X direction -10 11.1 -9.28 10.1 -10.2 11.2
Y direction -70.2 82.9 -78.4 39.9 -65.5 69.3
Z direction -96.6 82.5 -66.7 60.5 62.2 47.9
Total 92 76.7 68.6
Weight 1607.4 1607.4 1912．6
 
 
  According to calculation results, honeycomb girder improves the stiffness of main girder in the condition without any increased weight.
 
 
a. compared with box girder: stress at web plate centre of box girder is near to zero, to improve utility value of web plate, ZZHZ makes honeycomb hole in the web plate, thus inertia moment of main girder reduces little. Relatively speaking, material utility value is improved.
b. compared with truss girder: truss girder generally uses approximation method to calculate static stiffness of main girder, so its reduced moment of inertia usually is 0.7-0.8 times of moment of inertia of upper and lower chord of truss girder. Now contrastive analysis on gantry crane main girder is done as below (80t-32m gantry crane, working grade A5). Main girder drawing is as below:
 
 
According to gantry crane deflection calculation demands: as calculating deflection of 80t gantry crane, applied loads is rated lifting loads and self-weight loads of lifting trolley(with hook and spreader). Load in the calculation is about 88t. use BEAM4 and BEAM189 units for triangle truss girder calculation with finite element software; and use SHELL63 and BEAM4 units for honeycomb girder calculation. Calculation model is as follows: 
 
Truss girder gantry crane
 
 
 
Honeycomb girder gantry crane
 
Girder type Truss girder Honeycomb girder Remark 
Displacement mm X direction -3.77 0.32 -3.1 0.75 Deflection span ratio for truss girder1/747
Deflection span ratio for honeycomb girder1/837
Y direction -42.79 7.16 -38.2 6.4
Z direction -31.4 0.16 -29.7 0.16
Total 50.7 45.7
Stress 
MPa X direction -118 94.9 -126 111 The truss girder uses BEAM units, so stress on Y, Z direction is unknown
Y direction -132 109
Z direction -134 130
Total 118 135
Weight 33745kg 33319kg Weight of rail, rail clamping plates and ladder is not in consideration
 
Height of truss girder and honeycomb girder is as follows:
Truss girder height 2450mm
Honeycomb girder height 2400mm
With comparison of two main girders, inertia moment of truss girder is 0.785 times of that of upper and lower chord. Inertia moment of honeycomb girder is 0.974 times of that of continuous face. So as designing the honeycomb girder, box girder can be taken as a reference.
Practice has proved that: product made by ZZHZ features light self-weight, safe and reliable; will make a great contribution to national construction project.